str1= "hello world"
str2= 'hello world'
str3= '''hello world'''
print(str1)
print(str2)
print(str3)
print('hel\'lo world')#转义符
print(f'123---{0}---{1}---{2}'.format(4,5,6))
str1='hello'
print(f'123---{str1}')

for i in range(0,101,2):
    print("======开始下载=====")
    if i==100:
        print("======下载完成=====")
    else:
        str4="*"*(i//2)+"."*((100-i)//2)
        print(f'{i}%[{str4}]')